A DFT plus U look into experimentally synthesized monoclinic scheelite BiVO4

摘要

We present a combined experimental and Hubbard interaction corrected density functional theory (DFT+U) based study of monoclinic scheelite ( m s) bismuth vanadate BiVO4 (BVO). The m s-BVO samples were synthesized using the standard solid state reaction technique. The m s phase of the synthesized BVO samples has been confirmed from Rietveld analysis of the powder x-ray diffraction pattern and room temperature Raman spectroscopy. Both experimentally obtained crystal parameters and Raman peak positions were benchmarked against the DFT+U simulations. The variations in morphology and chemical concentrations due to different sintering temperatures and milling times were analyzed using field emission scanning electron microscopy and energy dispersive x-ray spectroscopy. The measured energy bandgap in the range of 2.38-2.58 eV from UV-Vis-NIR diffuse reflection spectroscopy was explained within the context of grain size variations in combination with bismuth and oxygen vacancies from DFT+U simulations.